Corrosion inhibitor composition, transport fluid mixture, method for charging corrosion inhibitor composition, winze, and pipeline

ABSTRACT

A corrosion inhibitor composition contains an organic long-chain compound having a polar group and hydrophobic silica. In a method for charging a corrosion inhibitor composition, the corrosion inhibitor composition constituted of a first corrosion inhibitor composition containing an organic long-chain compound having a polar group and a second corrosion inhibitor composition containing hydrophobic silica is charged into a fluid mixture including at least one hydrocarbon fluid selected from the group consisting of a liquid-phase hydrocarbon fluid and a gas-phase hydrocarbon fluid and water.

TECHNICAL FIELD

The present invention relates to a corrosion inhibitor composition, atransport fluid mixture, a method for charging a corrosion inhibitorcomposition, a winze, and a pipeline.

Priority is claimed on Japanese Patent Application No. 2018-002918,filed Jan. 11, 2018, the content of which is incorporated by reference.

BACKGROUND ART

A material of an oil extraction pipe (tubing) installed inside a casingin order to derive petroleum or natural gas from an oil layer or a gaslayer above ground in a producing well such as an oil deposit from whichpetroleum is produced or a gas deposit from which natural gas isproduced is mainly carbon steel or stainless steel. In addition, as amaterial of a transport pipe in a pipeline constructed to transportpetroleum or natural gas from a producing well to a treatment facilityor a delivery terminal, the same carbon steel or stainless steel as thatfor an oil extraction pipe is employed.

In crude oil or natural gas as mined from underground, a corrosive gassuch as carbon dioxide or hydrogen sulfide is included together withmoisture. Therefore, in an oil extraction pipe in a producing well or atransport pipe in a pipeline, the corrosion of the inner surface by sucha wet corrosive gas needs to be taken into account.

As a method for inhibiting the corrosion of metal on an outer surface ofa drill pipe used for the mining development of petroleum or naturalgas, for example, Patent Document 1 discloses a method in which, insuppressing the local corrosion of metals, an organic inhibitor(inhibitor) such as a long-chain fatty acid and a hydrocarbon oil suchas an aromatic hydrocarbon are added.

In addition, Patent Document 2 discloses a method for suppressing thecorrosion of iron-based metal by water in which the corrosion rate bywater is decreased by adjusting the concentration of silica in watercirculating in a pipe made of iron-based metal.

CITATION LIST Patent Document Patent Document 1

Japanese Unexamined Patent Application, First Publication No.2000-219980

Patent Document 2

Japanese Unexamined Patent Application, First Publication No.2004-132636

SUMMARY OF INVENTION Technical Problem

Patent Document 1 describes a method in which an amine-based organiccompound or lauric acid is used as an inhibitor and added to drillingmud together with a hydrocarbon oil such as iso-octane or xylene, whichdoes not necessarily satisfy the corrosion inhibition of metal on aninner surface of a drill pipe used for the mining development ofpetroleum or natural gas.

In the method used in Patent Document 2, a corrosion inhibition effectof hydrophilic silica such as sodium silicate or potassium silicateagainst water is confirmed, but a corrosion inhibition effect againstwet corrosive gas including carbon dioxide, hydrogen sulfide, or thelike exposed when used in a facility in a producing well such as an oildeposit in which a crude oil component is present in a mixture form or agas deposit.

The present invention has been made in consideration of theabove-described circumstance, and an object of the present invention isto provide a corrosion inhibitor composition, a transport fluid mixture,a method for charging a corrosion inhibitor composition, a winze, and apipeline which are capable of sufficiently inhibiting corrosion by wetcorrosive gas including carbon dioxide or hydrogen sulfide on an innersurface of an oil extraction pipe in a producing well or a transportpipe in a pipeline.

Solution to Problem

The present invention is characterized by having any of the followingaspects.

[1] A corrosion inhibitor composition including: an organic long-chaincompound having a polar group; and hydrophobic silica.

[2] The corrosion inhibitor composition according to [1] furtherincluding: an organic solvent.

[3] A transport fluid mixture including: at least one hydrocarbon fluidselected from the group consisting of a liquid-phase hydrocarbon fluidand a gas-phase hydrocarbon fluid; water; and a corrosion inhibitorcomposition containing an organic long-chain compound having a polargroup and hydrophobic silica.

[4] The transport fluid mixture according to [3] or [4], in which theorganic long-chain compound having a polar group has one or moreselected from nitrogen, oxygen, and sulfur.

[5] The transport fluid mixture according to [3] or [4], in which thecorrosion inhibitor composition further includes an organic solvent.

[6] The transport fluid mixture according to [5], in which the organicsolvent is a liquid phase at a temperature and a pressure that aretransport conditions of the transport fluid mixture.

[7] The transport fluid mixture according to [5] or [6], in which theorganic solvent is an aromatic compound.

[8] A method for charging a corrosion inhibitor composition including: acorrosion inhibitor composition charging step of charging a corrosioninhibitor composition into a fluid mixture including at least onehydrocarbon fluid selected from the group consisting of a liquid-phasehydrocarbon fluid and a gas-phase hydrocarbon fluid and water, in whichthe corrosion inhibitor composition is constituted of a first corrosioninhibitor composition containing an organic long-chain compound having apolar group and a second corrosion inhibitor composition containinghydrophobic silica.

[9] The method for charging the corrosion inhibitor compositionaccording to [8], in which the second corrosion inhibitor compositionfurther includes an organic solvent.

[10] The method for charging the corrosion inhibitor compositionaccording to [8] or [9], in which, in the corrosion inhibitorcomposition charging step, the first corrosion inhibitor composition andthe second corrosion inhibitor composition are separately charged intothe fluid mixture.

[11] A winze including: a tubing having an anticorrosive coating formedon an inner surface thereof by the corrosion inhibitor compositionaccording to [1] or [2].

The winze in the present invention is not limited to a producing wellsuch as an oil deposit or a gas deposit and includes a facility having apipe for which the corrosion of an inner surface by corrosive gas isconcerned such as an injection well for injecting gas or water into theunderground or an observation well for observing the underground stateduring the production of crude oil or natural gas.

[12] A pipeline including: a transport pipe having an anticorrosivecoating formed on an inner surface thereof by the corrosion inhibitorcomposition according to [1] or [2].

The pipeline in the present invention is a facility that transports amined fossil fuel such as petroleum or natural gas and does not refer toa simple assembly of pipes.

Advantageous Effects of Invention

According to the corrosion inhibitor composition of the presentinvention and the transport fluid mixture containing the corrosioninhibitor composition of the present invention, it is possible tosufficiently inhibit the corrosion of a member having an inner surfaceto be exposed to a liquid phase including wet corrosive gas such as anoil extraction pipe in a producing well or a transport pipe in apipeline.

In addition, according to the method for charging the corrosioninhibitor composition of the present invention, it is possible tosufficiently inhibit the corrosion of a member having an inner surfaceto be exposed to a liquid phase including wet corrosive gas such as anoil extraction pipe in a producing well or a transport pipe in apipeline by efficiently dispersing hydrophobic silica.

In addition, in the winze and the pipeline of the present invention, aninner surface of an oil extraction pipe or the transport pipe does noteasily corrode. Therefore, it is possible to extend the lifetime of theoil extraction pipe or the transport pipe, and it is possible tosuppress the operation cost of a facility.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view schematically showing an example of anoil extraction pipe included in a winze of the present invention.

FIG. 2 is a partial enlarged view of FIG. 1.

FIG. 3 is a schematic view showing individual facilities of an oildeposit intended for the production of petroleum.

FIG. 4 is a schematic view showing an example of a producing well ofFIG. 3.

FIG. 5 is a schematic view showing another example of the producing wellof FIG. 3.

FIG. 6 is a schematic view showing an example of a pipeline system ofFIG. 3.

FIG. 7 is a schematic view showing a device for measuring a corrosionrate, which is used in Test 1.

FIG. 8 is a graph showing results (corrosion inhibition percentage) ofTest 1.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an example of an embodiment of the present invention willbe described in detail, but the present invention is not interpreted tobe limited to this embodiment.

Corrosion Inhibitor Composition

A corrosion inhibitor composition of the present embodiment contains anorganic long-chain compound having a polar group capable of providing anelectron to metal and hydrophobic silica. The corrosion inhibitorcomposition of the present embodiment preferably further contains anorganic solvent.

Hereinafter, the respective components will be described.

Organic Long-Chain Compound

The organic long-chain compound has a polar group capable of providingan electron to metal and a long-chain hydrophobic group and is referredto as an inhibitor.

As the polar group capable of providing an electron to metal, polargroups including one or more elements selected from the group consistingof nitrogen (N), oxygen (O), and sulfur (S) are included. Specifically,as the polar group, a carboxy group and a salt thereof, a hydroxylgroup, a group having basic nitrogen (for example, an amino group or thelike) and a salt thereof, a sulfonic acid group and a salt thereof, andthe like are exemplified. As the salt, an alkali metal salt, analkaline-earth metal salt, and the like are exemplified.

In a case where the inner surface of an oil extraction pipe or apipeline is bare metal, a polar group including nitrogen is preferablyselected, and, in a case where a passive film is formed on the innersurface of a pipeline, a carboxy group is preferably selected as thepolar group.

The number of the polar groups may be one or more in one molecule or maybe two or more in one molecule. In a case where the organic long-chaincompound has two or more polar groups, the polar groups may be identicalto or different from each other in kind.

As the long-chain hydrophobic group, an alkyl group having 8 to 20carbon atoms, an alkenyl group having 8 to 20 carbon atoms, and the likeare exemplified.

When the polar group supplies an electron to metal, the organiclong-chain compound is adsorbed to the metal surface and forms a layer(film). Such an organic long-chain compound is also referred to as“absorptive inhibitor” or “filming amine”.

As the organic long-chain compound, for example, sodiumN-dodecanoylsarcosinate, dodecylamine, stearic acid, lauric acid, oleicimidazoline, and the like are exemplified.

In addition, a commercially available product may be used as the organiclong-chain compound, and, for example, a water-soluble inhibitor (tradename: “EC1304A”) and an oil-soluble and water-dispersive inhibitor(trade name: “EC1103A”) manufactured by Nalco Champion, and the like areexemplified.

These organic long-chain compounds may be used singly or two or moreorganic long-chain compounds may be jointly used.

In a facility in a producing well such as an oil deposit in which waterand a crude oil component are present in a mixture form or a gasdeposit, an amine-based organic long-chain compound having a smallerspecific gravity than water is not uniformly dispersed in a water phaseand has a possibility of weakening a corrosion inhibition effect in thebottom portion of the water phase in a pipeline or the like having astructure in which oil and water separate from each other.

Therefore, hydrophobic nano-fine particles, which are a hydrophobiccompound having a larger specific gravity than water, are morepreferably used.

In addition, the organic long-chain compound or the like has a highdispersibility in water and can be uniformly dispersed in a transportfluid mixture described below even when the proportion of water in thetransport fluid mixture increases.

Hydrophobic Silica

In the present embodiment, the hydrophobic silica forms an anticorrosivecoating together with the organic long-chain compound adsorbed to themetal surface.

The hydrophobic silica is obtained by surface-treating the silicasurface with a hydrophobic component. As a component forsurface-treating the silica surface, a silane coupling agent,polydimethylsiloxane, and the like are exemplified, and there is noparticular limitation. The hydrophobic silica used in the presentembodiment has a surface that has been surface-treated in advance with ahydrophobic component and is thus not easily precipitated in a stronglyalkaline solution or strongly acidic solution in which a divalent ortrivalent ion is present and is uniformly dispersed.

As the hydrophobic silica, hydrophobic silica having a larger specificgravity than water is preferably used, and the specific gravity relativeto water (4° C.) is preferably 1.8 to 2.4, and the specific gravity ismore preferably 2.0 to 2.2. When the specific gravity relative to wateris 1.8 or more, the hydrophobic silica is likely to sink in a waterphase at the time of using the corrosion inhibitor composition of thepresent invention in an oil extraction pipe, a pipeline, or the like ina facility in a producing well such as an oil deposit in which water anda crude oil component are present in a mixture form or a gas deposit,and thus it is possible to impart a corrosion inhibition effect to thebottom portion of the water phase even in a pipeline or the like havinga structure in which oil and water separate from each other. When thespecific gravity relative to water is 2.4 or less, it is possible todecrease the amount of the hydrophobic silica to be precipitated.

An average particle diameter of the hydrophobic silica is preferably 10to 15 nm in terms of a BET average particle diameter and more preferably11 to 12 nm in terms of a BET average particle diameter. When the BETaverage particle diameter is 10 nm or more, it is possible to dispersethe hydrophobic silica in the transport fluid mixture withoutagglomerating the hydrophobic silica, and, when the BET average particlediameter exceeds 15 nm, the hydrophobic silica easily agglomerates dueto a hydrophobic interaction, the secondary agglomerated hydrophobicsilica is likely to coarsen and is precipitated.

The BET average particle diameter of the hydrophobic silica can beconfirmed using a BET method.

In addition, a surface hydrophobilization rate of the hydrophobic silicais preferably high and is preferably 80% to 100%. In the presentembodiment, a hydrophobic silica having a surface hydrophobilizationrate of 100% is more preferably used. There is a tendency that, as thesurface hydrophobilization rate increases, the corrosion inhibitioneffect is more significantly exhibited.

A method for measuring the surface hydrophobilization rate of thehydrophobic silica is not particularly limited, and the surfacehydrophobilization rate can be approximately estimated from a contactangle of methanol with respect to the hydrophobic silica surface.

The content of the hydrophobic silica in the corrosion inhibitorcomposition is preferably 3 to 60 parts by mass and more preferably 6 to40 parts by mass with respect to 100 parts by mass of the organiclong-chain compound. When the content of the hydrophobic silica is 3parts by mass or more, the corrosion inhibition effect is furtherenhanced. There is a tendency that, as the content of the hydrophobicsilica increases, the corrosion inhibition effect is further enhanced;however, when the content exceeds 40 parts by mass, the improvement ofthe effect hits a peak. When the balance between the corrosioninhibition effect and the manufacturing cost is taken into account, thecontent of the hydrophobic silica is preferably 60 parts by mass orless.

Organic Solvent

The organic solvent can be used to efficiently disperse the hydrophobicsilica.

While described below, the transport fluid mixture in an oil extractionpipe, a pipeline, or the like in a facility in a producing well such asan oil deposit in which water and a crude oil component are present in amixture form or a gas deposit may contain the corrosion inhibitorcomposition of the present embodiment. As described above, when thecorrosion inhibitor composition of the present embodiment is containedin the transport fluid mixture, the organic solvent is preferably aliquid phase at a temperature and a pressure that are the transportconditions of the transport fluid mixture.

The temperature and the pressure of the transport fluid mixture exhibitintrinsic values in an oil deposit and a gas deposit respectively. Asthe organic solvent that is a liquid phase at the temperature and thepressure, hydrocarbons having 8 to 20 carbon atoms, paraffin,cycloparaben, naphtha, light oil, heavy oil, crude oil, and an aromaticcompound such as a monocyclic aromatic hydrocarbon having one aromaticring in one molecule or a polycyclic aromatic hydrocarbon having two ormore aromatic rings in one molecule are exemplified.

As the organic solvent, a monocyclic aromatic hydrocarbon is preferred,and a monocyclic aromatic hydrocarbon having a boiling point of 60° C.to 200° C. under a pressure condition of 0.1 MPa is particularlypreferred since the organic solvent is favorably compatible with theorganic long-chain compound, is capable of highly dispersing thehydrophobic silica, and more easily exhibits the (corrosion inhibition)effect of the present embodiment. The boiling point of the monocyclicaromatic hydrocarbon is more preferably 70° C. to 180° C. and still morepreferably 80° C. to 150° C. under a pressure condition of 0.1 MPa.Since the (corrosion inhibition) effect of the present embodiment ismore easily exhibited when the corrosion inhibitor composition is usedat a higher temperature and a higher pressure (for example, atemperature higher than 100° C. and a pressure higher than 10 MPa) (thatis, the use of the corrosion inhibitor composition in an environment inwhich a transport pipe in an oil extraction pipe or a pipeline in aproducing well is exposed to a high temperature and a high pressure), asthe organic solvent, a polycyclic aromatic hydrocarbon is preferablyused, and it is possible to select the use of a polycyclic aromatichydrocarbon and, as the organic long-chain compound, an amine-basedcompound such as dodecylamine, stearic acid, or oleic imidazoline incombination.

As the monocyclic aromatic hydrocarbon, for example, benzene (boilingpoint: 80.1° C.), toluene (boiling point: 110.6° C.), xylene (boilingpoint: 138° C. to 144° C.), ethylbenzene (boiling point: 136° C.), andthe like are exemplified. These monocyclic aromatic hydrocarbons may beused singly or two or more monocyclic aromatic hydrocarbons may bejointly used.

As the polycyclic aromatic hydrocarbon, SOLVESSO 100, SOLVESSO 150, andSOLVESSO 200 manufactured by Exxon Mobil Corporation, and the like areexemplified. These polycyclic aromatic hydrocarbons may be used singlyor two or more polycyclic aromatic hydrocarbons may be jointly used.

The content of the organic solvent in the corrosion inhibitorcomposition is preferably 100 to 2,000 parts by mass and more preferably300 to 1,500 parts by mass with respect to 100 parts by mass of theorganic long-chain compound. When the content of the organic solvent is100 parts by mass or more, the enhancement of the corrosion inhibitioneffect by the addition of the organic solvent can be obtained. There isa tendency that, as the content of the organic solvent increases, thecorrosion inhibition effect is further enhanced; however, when thecontent exceeds 2,000 parts by mass, the improvement of the effect hitsa peak. When the balance between the corrosion inhibition effect and themanufacturing cost is taken into account, the content of the organicsolvent is preferably 1,000 parts by mass or less.

Random Component

The corrosion inhibitor composition of the present embodiment mayinclude a random component as necessary as long as the effect of thepresent embodiment is not impaired.

As the random component, for example, alcohols having a low molecularweight (specifically, having 1 to 10 carbon atoms) such as ethanol andthe like are exemplified. When the corrosion inhibitor compositionincludes the alcohol having a low molecular weight, the dispersibilityof the organic long-chain compound in water is further enhanced.

Action and Effect

The corrosion inhibitor composition of the present embodiment containsthe organic long-chain compound and the hydrophobic silica and is thusexcellent in terms of corrosion inhibition performance. In addition,when containing the organic long-chain compound, the hydrophobic silica,and the organic solvent, the corrosion inhibitor composition of thepresent embodiment is superior in terms of corrosion inhibitionperformance.

Particularly, the corrosion inhibitor composition of the presentembodiment exhibits an excellent effect even on a pipe inner surface inwhich the suppression of corrosion with a corrosion inhibitor of therelated art is difficult and oil and water separate from each other andwhich is wetted by water. Therefore, the corrosion inhibitor compositionof the present embodiment is capable of sufficiently inhibiting thecorrosion of the inner surface of an oil extraction pipe or a transportpipe. The reason for the corrosion inhibitor composition of the presentembodiment being excellent in terms of corrosion inhibition performanceis considered as follows.

When an anticorrosive coating is formed on, for example, the innersurface of an oil extraction pipe by the corrosion inhibitor compositionof the present embodiment, as shown in FIG. 1, an oil extraction pipe 10having an anticorrosive coating 12 made of the corrosion inhibitorcomposition formed on an inner surface 11 a of a main body 11 isobtained. Specifically, this anticorrosive coating 12 is considered tobe formed as described below as schematically shown in FIG. 2.

First, the polar group of the organic long-chain compound is adsorbed tothe inner surface 11 a of the main body 11, and a layer (hereinafter,referred to as “A layer”) 12 a mainly made of the organic long-chaincompound is formed. Furthermore, the hydrophobic silica and the organicsolvent are tangled with the hydrophobic group of the organic long-chaincompound. For example, in the case of charging the hydrophobic silicaand the organic solvent together, a layer (hereinafter, referred to as“B layer”) 12 b mainly made of the organic solvent and a layer(hereinafter, referred to as “C layer”) 12 c mainly made of thehydrophobic silica are formed on the A layer 12 a, thereby forming theanticorrosive coating 12. The anticorrosive coating 12 may be formed byforming the C layer 12 c on the A layer 12 a, and, in FIG. 2, the Alayer 12 a, the B layer 12 b, and the C layer 12 c are differentiatedfrom each other in order to schematically show the anticorrosive coating12 for description, but interfaces between these layers are not clear.

In addition, in the case of forming the A layer 12 a, the B layer 12 b,and the C layer 12 c, the polar group of the organic long-chain compoundis adsorbed to the inner surface 11 a of the main body 11 to form the Alayer 12 a, and the organic solvent tangles with the hydrophobic groupof the organic long-chain compound to form the B layer 12 b, whereby thecorrosion inhibition effect of the organic long-chain compound isenhanced, and a corrosion inhibition property is exhibited. It isconsidered that, when the C layer 12 c is formed by using thehydrophobic silica in addition to the organic long-chain compound andthe organic solvent, stability improves, and the corrosion inhibitioneffect is further enhanced, whereby the corrosion inhibition propertyimproves, and the corrosion of the inner surface of an oil extractionpipe or a transport pipe can be sufficiently inhibited.

In the case of forming the anticorrosive coating 12 by forming the Clayer 12 c on the A layer 12 a, the C layer 12 c may be formed by thetangling of the hydrophobic silica with the hydrophobic group of theorganic long-chain compound or the B layer 12 b and the C layer 12 c maybe formed by the tangling of an organic solvent derived from a crude oilcomponent being communicated in the main body 11 with the hydrophobicgroup of the organic long-chain compound together with the hydrophobicsilica.

The corrosion inhibitor composition of the present embodiment ispreferred as a corrosion inhibitor composition for an oil extractionpipe in a producing well for producing petroleum, natural gas, or thelike or a transport pipe in a pipeline for transporting petroleum ornatural gas in which the inner surface of the transport pipe or the likeis exposed to a liquid phase including wet corrosive gas and is,specifically, used to form an anticorrosive coating on the inner surfaceof an oil extraction pipe or a transport pipe.

Transport Fluid Mixture

A transport fluid mixture of the present embodiment is used to form ananticorrosive coating in an oil extraction pipe or a pipeline.

The transport fluid mixture of the present embodiment is a fluid passingthrough an oil extraction pipe, a pipeline, or the like in a producingwell such as an oil deposit in which water and a crude oil component arepresent in a mixture form or a gas deposit and contains at least onehydrocarbon fluid selected from the group consisting of a liquid-phasehydrocarbon fluid and a gas-phase hydrocarbon fluid, water, and thecorrosion inhibitor composition.

The hydrocarbon fluid in the present embodiment includes crude oil asmined, natural gas as mined, and, furthermore, corrosive gas such ascarbon dioxide or hydrogen sulfide.

The water in the present embodiment may be groundwater as mined or maybe water being added to be introduced to an injection well andaccelerate the collection of crude oil and natural gas when crude oil,natural gas, and groundwater do not flow from a producing well.

In the transport fluid mixture of the present embodiment, the corrosioninhibitor composition of the present embodiment can be used even in astate in which the water is groundwater alone and the ratio of thehydrocarbon fluid, which is an oil, is high (for example, oil(hydrocarbon fluid):water=95 to 75 parts by mass:5 to 25 parts by massand also can be used even after water for accelerating the collection ofcrude oil and natural gas is added. Specifically, the transport fluidmixture can be used even when the ratio between the oil (hydrocarbonfluid):water=10 to 30 parts by mass:90 to 70 parts by mass. This isrealized by adjusting the property and specific gravity of the organiclong-chain compound and/or the specific gravity of the hydrophobicsilica in the corrosion inhibitor composition of the present embodiment.

Method for Charging Corrosion Inhibitor Composition

In the present embodiment, the corrosion inhibitor compositionconstituted of the first corrosion inhibitor composition including anorganic long-chain compound having a polar group and the secondcorrosion inhibitor composition including hydrophobic silica is chargedinto the fluid mixture including the hydrocarbon fluid and water. Thesecond corrosion inhibitor composition may contain an organic solventand a random component added as necessary. In a case where the secondcorrosion inhibitor composition contains an organic solvent, adispersion solution may be prepared in advance by mixing the organicsolvent and hydrophobic silica.

The first corrosion inhibitor composition and the second corrosioninhibitor composition including hydrophobic silica are preferablycharged separately while the order is not limited.

Particularly preferably, it is preferable to charge the first corrosioninhibitor composition and then charge the second corrosion inhibitorcomposition because the efficiency of the formation of the anticorrosivecoating is improved.

Winze and Pipeline

A winze and a pipeline of the present embodiment includes a steel pipehaving an anticorrosive coating formed on an inner surface using theabove-described corrosion inhibitor composition of the presentembodiment as an oil extraction pipe in a producing well or a transportpipe in a pipeline. The inner surface refers to an inside surface of anoil extraction pipe or a transport pipe and is a surface which crude oilor natural gas including wet corrosive gas comes into contact with.

An outer surface of the oil extraction pipe or the transport pipe may becoated with a coating layer as necessary.

As the coating layer coating the outer surface, for example, a coatinglayer having a structure in which a primer layer, an adhesive layer, anda polyolefin layer are sequentially laminated from an outer surface sideis exemplified. The primer layer is formed of, for example, an epoxyresin. The polyolefin layer is formed of at least one of polyethyleneand polypropylene and may be a single layer or a multilayer.

FIG. 1 is a cross-sectional view showing an example of an oil extractionpipe included in the winze of the present embodiment. As describedabove, the oil extraction pipe 10 in this example has the anticorrosivecoating 12 made of the corrosion inhibitor composition formed on theinner surface 11 a of the main body 11.

The amount of the organic long-chain compound attached to one squaremeter of the inner surface 11 a of the main body 11 is preferably 0.1 to3 mg.

In addition, the amount of the hydrophobic silica attached to one squaremeter of the inner surface 11 a is preferably 0.4 mg to 0.9 g.

In addition, the amount of the organic solvent attached to one squaremeter of the inner surface 11 a is 20 mg to 3 g.

What has described above is also true for the amounts of the organiclong-chain compound, the hydrophobic silica, and the organic solventattached to one square meter of the inner surface of the pipeline.

Here, an example of a method for forming the anticorrosive coating 12 onthe inner surface 11 a of the pipe will be described with reference toFIG. 3. FIG. 3 shows an oil deposit intended for the production ofpetroleum. The oil deposit includes a producing well 20 that mines crudeoil from an underground oil layer 1, a separator 31 that separates animpurity such as natural gas or ground water from non-treated crude oil,an oil storage tank 32 that stores the crude oil from which the impurityis separated, and a pipeline system 34 that transports the crude oilfrom the oil storage tank 32 to a treatment facility 33.

FIG. 4 shows the structure of, particularly, the producing well 20 inthe oil deposit. The producing well 20 includes a tubular casing 21reaching up to the oil layer 1 and a tubing 22 as an oil extraction pipepassing through the inside of the casing 21. A plurality of small holesis formed on a lower end wall surface of the casing 21.

An entry guide 23 that introduces a produced fluid to the inside of thetubing 22 is connected to a lower end of the tubing 22 reaching the oillayer 1. A winze device 24 including equipment (not shown) such as avalve, a pressure meter, a thermometer, and a blowout inhibition deviceis attached to an upper end portion of the tubing 22 exposed on theground.

A first tank 25 and a second tank 51 into which the corrosion inhibitorcomposition of the present embodiment is fed are connected to the winzedevice 24. The first corrosion inhibitor composition including theorganic long-chain compound having a polar group is introduced from thefirst tank 25, and the second corrosion inhibitor composition includingthe hydrophobic silica is introduced from the second tank 51. The firsttank 25 and the second tank 51 communicate with the tubing 22 through acharging pipe 26. A pump 27 that pressurizes and supplies the corrosioninhibitor composition to the inside of the tubing 22 is provided in thecharging pipe 26.

Crude oil present in the oil layer 1 flows to the inside of the tubing22 from the entry guide 23. In a case where the pressure of the oillayer 1 is high, the crude oil flows from the winze through the tubing22; however, in a case where the pressure of the oil layer 1 is low, thecrude oil is drawn to the ground using a drawing pump or the like, notshown. The crude oil mined from the oil layer 1 through the tubing 22 istransported to the separator 31 through the winze device 24, temporarilykept in the oil storage tank 32 after the separation of an impurity, andthen transported to the treatment facility 33 through the pipelinesystem 34.

As a method for forming the anticorrosive coating on the inner surfaceof the tubing 22 using the corrosion inhibitor composition, there are amethod in which the production of crude oil is temporarily stopped andthen the anticorrosive coating is formed and a method in which theanticorrosive coating is formed while continuing the production of crudeoil.

First, the method in which the production of crude oil is stopped andthen the anticorrosive coating is formed will be described. The valve inthe winze device 24 is closed, thereby making the inside of the tubing22 a space closed except for the portion of the entry guide 23 at thefront end. In the inside of the tubing 22 made to be a closed space,natural gas, ground water, and, furthermore, crude oil as minedincluding corrosive gas such as carbon dioxide or hydrogen sulfide aresealed. A pump 27 is operated while maintaining this state, therebycharging the corrosion inhibitor composition into the inside of thetubing 22. In a producing well in which the pressure of the oil layer 1is high and crude oil flows, the corrosion inhibitor composition ispressurized at a pressure higher than that of the oil layer 1 whilemaintaining the sealing of the tubing 22, thereby charging the corrosioninhibitor composition into the inside of the tubing 22.

In a producing well in which the pressure of the oil layer 1 is low andcrude oil does not flow, the corrosion inhibitor composition may besupplied to the inside of the tubing 22 while keeping the valve in thewinze device 24 opened.

The corrosion inhibitor composition supplied to the inside of the tubing22 sinks in the inside of the tubing 22, and, in such a process, therespective components of the organic long-chain compound, the organicsolvent, and the hydrophobic silica are attached to the inner surface ofthe tubing 22, whereby the anticorrosive coating 12 constituted of the Alayer 12 a, the B layer 12 b, and the C layer 12 c shown in FIG. 2 isformed.

Next, the method in which the anticorrosive coating is formed on theinner surface of the tubing 22 while continuing the production of crudeoil will be described. As shown in FIG. 5, a charging pipe (capillarytube) 26 having so sufficient a length that a front end reaches theentry guide 23 is mounted in the inside of the tubing 22, and the pump27 is operated as necessary, thereby supplying the corrosion inhibitorcomposition to the inside of the tubing 22.

The corrosion inhibitor composition is charged into the inside of thetubing 22 from the front end of the charging pipe 26 reaching the entryguide 23, circulates in the inside of the tubing 22 together with thecrude oil flowing to the ground from the oil layer 1, and, in such aprocess, the respective components of the organic long-chain compound,the organic solvent, and the hydrophobic silica are attached to theinner surface of the tubing 22, whereby the anticorrosive coating 12constituted of the A layer 12 a, the B layer 12 b, and the C layer 12 cshown in FIG. 2 is formed.

With the above-described methods, it is also possible to form theanticorrosive coating 12 on the inner surface of the existing tubing 22in a producing well.

The anticorrosive coating is formed on the inner surface of thepipeline, for example, as described below.

FIG. 6 shows the pipeline system 34 that transports crude oil to thetreatment facility 33 (refer to FIG. 3) from the winze device 24 throughthe separator 31 and the oil storage tank 32. The pipeline system 34includes a pneumatic transportation facility 35 that pneumaticallytransports the crude oil temporarily stored in the oil storage tanktoward a refinery, a pipeline 36 connecting a number of transport pipes,and a receiving facility 37 that receives the crude oil pneumaticallytransported through the pipeline 36 in the refinery.

The first tank 25 and the second tank 51 into which the corrosioninhibitor compositions are fed are connected to the winze device 24. Thefirst tank 25 and the second tank 51 are connected to the winze device24 through the charging pipe 26 and communicate with the pipeline 36through the separator 31 and the oil storage tank 32. The pump 27 thatpressurizes and supplies the corrosion inhibitor composition to theinside of the pipeline 36 through the winze device 24 is provided in thecharging pipe 26.

At the time of forming the anticorrosive coating on the inner surface ofthe pipeline 36 using the corrosion inhibitor composition, when thecorrosion inhibitor composition is charged into the inside of thepipeline 36 through the winze device 24 by operating the pump 27, thecorrosion inhibitor composition circulates in the inside of the pipeline36 together with the crude oil, and, in such a process, the respectivecomponents of the organic long-chain compound, the organic solvent, andthe hydrophobic silica are attached to the inner surface of the pipeline36, whereby the anticorrosive coating 12 constituted of the A layer 12a, the B layer 12 b, and the C layer 12 c shown in FIG. 1 is formed.

With the above-described method, it is also possible to form theanticorrosive coating 12 on the inner surface of a transport pipeconfiguring the existing pipeline 36.

Because the anticorrosive coating is formed using the corrosioninhibitor composition of the present embodiment on the inner surfaces ofthe tubing and the pipeline, and thus the winze and the pipeline of thepresent embodiment described above do not easily corrode.

In addition, in the present embodiment, after the anticorrosive coatingis formed on the inner surfaces of the tubing and the pipeline, crudeoil or natural gas including wet corrosive gas may be circulated bystopping the circulation of the corrosion inhibitor composition.

That is, because the corrosion inhibitor composition of the presentembodiment forms an anticorrosive coating, it is not necessary tocirculate the corrosion inhibitor composition while an oil extractionpipe or a pipeline in a facility in a producing well such as an oildeposit or a gas deposit is in operation.

EXAMPLES

Hereinafter, the present invention will be more specifically described,but the present invention is not limited thereto.

Test 1 Example 1

A corrosion rate was measured using a device 40 shown in FIG. 7. Thedevice 40 shown in FIG. 7 was equipped with a sealable glass container41 having a capacity of 1.0 L (glass cell), addition means 42 for addinga chemical to the glass container 41), charging means 43 for charging agas such as carbon dioxide into the glass container 41, dischargingmeans 44 for discharging the gas from the glass cell 41, electrodes 45,and stirring means 46.

A heater 41 a was attached to an outer circumference of the glass cell41 so as to be capable of holding the temperature of a solutioncontained in the glass cell 41 constant.

The electrodes 45 included a reference electrode 45 a, an actionelectrode 45 b, and a counter electrode 45 c. In the present example,carbon steel electrodes were used as the reference electrode 45 a andthe action electrode 45 b, and platinum was used as the counterelectrode 45 c.

Sodium hydrogen carbonate was added to a sodium chloride aqueoussolution having a concentration of 1% by mass (500 mL) such that theconcentration reached 400 mg/L, and hydrochloric acid was added theretosuch that the pH reached 3.9 at room temperature (25° C.), therebypreparing a test water.

The full amount of the obtained test water was fed into the glass cell41, a small current was caused to flow between the reference electrode45 a and the action electrode 45 b while stirring the test water in anopened state, a potential difference between the electrodes wascontrolled to a predetermined set potential (10 mV), and a currentdensity flowing between the action electrode 45 b and the counterelectrode 45 c was measured.

The potential was controlled by sweeping the potential from a corrosionpotential toward an anode side at a certain potential sweep rate.

The corrosion rate was obtained using a polarization resistance methodon the basis of the obtained results of the potential and the currentdensity. This was regarded as a corrosion rate (r₀) at the time ofblank. The corrosion rate (r₀) at the time of blank was 44 mpy.

Separately, the same amount of the test water was fed into the glasscell 41, a first corrosion inhibitor composition including an organiclong-chain compound and a second corrosion inhibitor compositionincluding an organic solvent and hydrophobic silica were separatelyadded thereto from the addition means 42, and a corrosion rate (r₁) peramount of the corrosion inhibitor composition added was obtained in thesame manner as the corrosion rate (r₀) while stirring the components inan opened state.

A corrosion inhibition percentage at the time of blank (that is, beforethe addition of a corrosion inhibitor) was regarded as 0%, and acorrosion inhibition percentage after the addition of the corrosioninhibitor was obtained using Expression (1) from the corrosion rate (r₀)and the corrosion rate (r₁). The results are shown in FIG. 8.

Corrosion inhibition percentage (%)={(r ₀ −r ₁)/r0}×100   (1)

Laurylamine (concentration: 2×10⁻⁴ mol/L, specific gravity relative towater: 0.8) was used as the organic long-chain compound, xylene was usedas the organic solvent, and ORGANOSILICASOL (TOL-ST, (BET averageparticle diameter: 10 to 15 nm, surface hydrophobilization rate: 100%,specific gravity relative to water: 2.2)) manufactured by NissanChemical Corporation was used as the hydrophobic silica.

Specifically, first, the corrosion rate (r₁) at the time of adding onlylaurylamine (concentration: 2×10⁻⁴ mol/L) (37 mg) was obtained, and thecorrosion inhibition percentage was calculated. The corrosion inhibitionpercentage in the case of adding only laurylamine was 32%.

Next, the corrosion rate (r₁) at the time of adding ORGANOSILICASOL (2mg) to xylene (0.1 cc, 80 mg) was obtained, and the corrosion inhibitionpercentage was calculated. The corrosion inhibition percentage at thistime was 32%.

Furthermore, xylene (0.1 cc, 80 mg) and ORGANOSILICASOL (2 mg) wereadded stepwise, the corrosion rates (r₁) were obtained respectively forratios of (ORGANOSILICASOL (mg)/xylene (cc) being 4 mg/0.2 cc, 6 mg/0.3cc, 8 mg/0.4 cc, 10 mg/0.5 cc, 12 mg/0.6 cc, and 14 mg/0.7 cc, and thecorrosion inhibition percentages were calculated.

The corrosion inhibition percentages were 56%, 66%, 80%, 86%, 89%, and91% in order, and the results are shown in FIG. 8.

In Example 1, with respect to 100 parts by mass of the organiclong-chain compound, the hydrophobic silica was added stepwise in fiveparts by mass increments, and the organic solvent was added stepwise in220 parts by mass increments.

Comparative Example 1

First, only laurylamine (concentration: 2×10⁻⁴ mol/L) (37 mg) was addedin the same manner as in Example 1.

After that, the corrosion rates (r₁) at the time of adding, instead ofthe corrosion inhibitor composition of the present invention, onlyxylene, which was an organic solvent, (0.2 cc, 0.4 cc, 0.6 cc, and 0.7cc) were obtained, and the corrosion inhibition percentages werecalculated.

The corrosion inhibition percentages were 36%, 59%, 62%, and 64% inorder, and the results are shown in FIG. 8.

In Comparative Example 1, with respect to 100 parts by mass of theorganic long-chain compound, the organic solvent was added stepwise in440 parts by mass increments.

As is clear from the results in FIG. 8, in Example 1, due to theaddition of the corrosion inhibitor composition of the presentinvention, the corrosion inhibition percentage increased up toapproximately 90% compared with that before the addition of thecorrosion inhibitor composition (blank). This result showed that, whilebeing a component that easily disperses in a hydrophobic hydrocarbonfluid, the corrosion inhibitor composition of the present inventiondispersed even in water and exhibits a corrosion inhibition effectagainst wet corrosive gas including carbon dioxide or the like.

On the other hand, in Comparative Example 1, the corrosion inhibitionpercentage increased to a certain extent (approximately 65%) due to theaddition of laurylamine, which was an organic long-chain compound, andxylene, which was an organic solvent, but was poorer compared with thatin Example 1.

INDUSTRIAL APPLICABILITY

According to the corrosion inhibitor composition of the presentinvention, it is possible to sufficient inhibit the corrosion of amember having an inner surface to be exposed to a liquid phase includingwet corrosive gas such as an oil extraction pipe in a producing well ora transport pipe in a pipeline in a producing well such as an oildeposit or a gas deposit. In addition, according to the corrosioninhibitor composition of the present invention, in a transport fluidmixture passing through an oil extraction pipe in a producing well, atransport pipe in a pipeline, or the like in a producing well such as anoil deposit or a gas deposit, it becomes possible to exhibit a corrosioninhibition effect against wet corrosive gas even when, for example, thecontent proportion of water becomes high.

REFERENCE SIGNS LIST

10 Oil extraction pipe

11 Main body

12 Anticorrosive coating

20 Producing well

22 Tubing (oil extraction pipe)

23 Entry guide

34 Pipeline system

36 Pipeline (transport pipe)

1. A corrosion inhibitor composition comprising: an organic long-chaincompound having a polar group; and hydrophobic silica.
 2. The corrosioninhibitor composition according to claim 1, further comprising: anorganic solvent.
 3. A transport fluid mixture comprising: at least onehydrocarbon fluid selected from the group consisting of a liquid-phasehydrocarbon fluid and a gas-phase hydrocarbon fluid; water; and acorrosion inhibitor composition containing an organic long-chaincompound having a polar group and hydrophobic silica.
 4. The transportfluid mixture according to claim 3, wherein the organic long-chaincompound having a polar group has one or more selected from nitrogen,oxygen, and sulfur.
 5. The transport fluid mixture according to claim 3,wherein the corrosion inhibitor composition further includes an organicsolvent.
 6. The transport fluid mixture according to claim 5, whereinthe organic solvent is a liquid phase at a temperature and a pressurethat are transport conditions of the transport fluid mixture.
 7. Thetransport fluid mixture according to claim 5, wherein the organicsolvent is an aromatic compound.
 8. A method for charging a corrosioninhibitor composition comprising: a corrosion inhibitor compositioncharging step of charging a corrosion inhibitor composition into a fluidmixture including at least one hydrocarbon fluid selected from the groupconsisting of a liquid-phase hydrocarbon fluid and a gas-phasehydrocarbon fluid and water, wherein the corrosion inhibitor compositionis constituted of a first corrosion inhibitor composition containing anorganic long-chain compound having a polar group and a second corrosioninhibitor composition containing hydrophobic silica.
 9. The method forcharging the corrosion inhibitor composition according to claim 8,wherein the second corrosion inhibitor composition further includes anorganic solvent.
 10. The method for charging the corrosion inhibitorcomposition according to claim 8, wherein, in the corrosion inhibitorcomposition charging step, the first corrosion inhibitor composition andthe second corrosion inhibitor composition are separately charged intothe fluid mixture.
 11. A winze comprising: a tubing having ananticorrosive coating formed on an inner surface thereof by thecorrosion inhibitor composition according to claim
 1. 12. A pipelinecomprising: a transport pipe having an anticorrosive coating formed onan inner surface thereof by the corrosion inhibitor compositionaccording to claim 1.